1. Field of the Invention
The present invention relates to a single crystal producing apparatus to be used for raising single crystals by a CZ method and a single crystal producing method using the same.
2. Discussion of the Background
A single crystal producing apparatus to be used for raising single crystals by a CZ method comprises a main chamber and a pull chamber coupled onto the main chamber. The main chamber is a cylindrical metallic vessel capable of closing the bottom face and opening, closing the top face. Conventionally the metallic vessel is fixed onto the floor face. Within the main chamber is constructed a hot zone. As hot zone components, a crucible, a cylindrical heater to be placed on the external side of the crucible, an adiabatic material to be placed under and around the heater.
In the pulling up the single crystals, a pull chamber is separated from a main chamber and hot zone components are set within a main chamber in a condition where a cover portion for closing the top face of the main chamber is disengaged. Then, the cover portion is engaged and the pull chamber is coupled, so as to start producing single crystals.
In the pulling up operation of the single crystals, a raw material within the crucible is heated and melted. The single crystals are pulled up from the molten liquid within the crucible with a wire hanging from the upper portion of a pull chamber. The pulled single crystals are drawn into the pull chamber. After the pulling up operation of the single crystals are completed, the cooling operation of the apparatus is allowed to wait. The pull chamber is separated and the single crystals accommodated within the pull chamber are taken out. The cover portion is disengaged from and the hot zone components within the main chamber are overhauled. After the reproducing operation (cleaning and exchanging operations), the components are assembled again to prepare for the pulling up of the next single crystals.
In such a single crystal producing apparatus, a cooling operation of the apparatus is allowed to wait after the completion of the pulling up operation of the single crystals. The "chamber decomposition", overhauling, reproducing and assembling and "chamber assembling" operations are conducted in order. Since the next pulling up operation cannot be conducted before the steps are completed, the availability of the apparatus is extremely low. Time required to the next pulling up start including the cooling operation of the apparatus is 10 hours.
In the producing operation of the single crystals, a clean environment is required. Thus, a single crystal producing apparatus is set in a clean pulling up chamber. Dust amount within the pulling up chamber increases through the overhauling, reproducing and assembling operations of the hot zone components, thereby causing risks of lowering the quality of the single crystals.